import React, { Component } from 'react'

function SonA(props) {
    return <div>
        <span>SonA</span>
        <button onClick={props.changeCount}>add</button>
    </div>
}

function SonB(props) {
    return <div>SonB -- {props.count}</div>
}


export default class App extends Component {

    state = {
        count: 0
    }

    changeCount() {
        this.setState({
            count: this.state.count + 1
        })
    }

    render() {
        return (
            <div>
                <h2> 父组件</h2>
                <SonA changeCount={this.changeCount.bind(this)} />
                <SonB count={this.state.count} />
            </div>
        )
    }
}